1. Field of the Invention
The present invention relates to a method and an apparatus for providing the inner surface of pipe lines such as those made of steel or the like metal, concrete or porcelain pipes or rigid resinous pipes, with a flexible tubular lining material through a binder under pressure. More particularly, the present invention relates to a method and an apparatus for providing the inner surface of pipe lines, chiefly those already constructed for various purposes on or under the ground, for example, underground pipe lines such as gas conduits, city water pipes and pipes enclosing power transmission wires or telephone cables, with a flexible lining material to reinforce the pipe lines or to repair damaged portions thereof.
2. Description of the Prior Art
It is well known that when underground pipe lines for gas or water are superannuated or damaged, gas or water leaks out causing many problems and that deteriorated pipe lines or casings enclosing power transmission wires or telephone cables result in accidents caused by electric leakage or crosstalk. A countermeasure from the past to prevent these problems is that when such underground pipe lines are superannuated, the pipe lines are dug up over the length of several ten to several hundred meters and replaced with new ones. In this case, however, supply of city water or gas has to be discontinued for a long period of time until the pipe replacing works have been finished. In the case where superannuated pipes are buried under public roads, the public encounters much trouble and inconvenience since traffic on the roads is limited during the work for digging up such superannuated pipes and replacing them with new ones. Further, much labor and cost are required for renewing the pipes in addition to difficulty in the work itself for pipe exchange. Once more, it is not unusual that many of the known methods for renewing the deteriorated or damaged pipes cannot be utilized, due to the particular situations of the place where such pipes are buried. In recent years, a strong probability of a big earthquake has been reported in many places in the world with the development of earthquake-predicting technique and a consideration is being given to reinforcing underground pipes, regardless of whether such pipes are superannuated or not, to protect them from damage anticipated possible by earthquakes.
A method for lining pipes, especially those buried in the ground without the necessity of digging up the buried pipes wherein a flexible tube is inserted into underground pipes and bonded to the inner surface thereof with the aid of a binder is already proposed for attaining both purposes of repairing damaged portions of the pipes and reinforcing the pipes so as to withstand strong mechanical shock as produced by an earthquake. In such a method, however, the step for inserting the flexible tube into the underground pipes is extremely difficult so that the work is almost impossible to operate in such places where the pipes are long or are curved in several portions. Developed recently under such circumstances is a method for providing pipes with a lining simultaneously with evagination wherein a flexible tube is inserted into a pipe while truning the tube inside out by the action of a pressurized fluid such as compressed air and bonded at the same time onto the inner surface of the pipe by the aid of a binder. The method of this type is disclosed in U.S. Pat. Nos. 2,794,758 and 3,132,062 and Japanese Patent Unexamined Publn. No. Sho. 55-39362. In these methods, a flexible tubular lining material is placed in a pressure tank and inserted into pipe lines simultaneously with evagination under pressure. These methods are certainly advantageous in that insertion of a lining material into a pipe is easy and requires only a short period of time; the lining material is easily applied onto the inner surface of the pipe; and the treatment is applicable to pipes of larger or smaller diameters. However, these methods are not practical for lining a pipe line of 200 m or more in length because the pressure container becomes too big for accommodating the bulky lining material.
A lining method to enable lining of a very long pipe line was successively developed wherein a long lining material is placed outside the pressure container and continuously fed thereinto. This improved method need not use a big pressure container and is classified into two types; one using a lining material previously provided on its inner surface with a binder and the other applying a binder onto the inner surface of a lining material simultaneously with or just before evagination of the lining material. The former type method is disclosed in U.S. Pat. No. 4,064,211 and U.K. Pat. No. 1,069,623 while the latter type method in U.S. Pat. No. 4,182,262; U.K. Pat. No. 1,044,645 and Japanese Patent Unexamined Publn. No. Sho. 55-90326. However, both types of these improved methods still have drawbacks, particularly in that when a lining material is introduced into the pressure container, a binder applied previously or just before introduction into the container onto the inner surface of the lining material is pushed backward by the internal fluid pressure to disturb even application of the binder onto the inner surface of the lining material, thus resulting in a great obstacle to assure bonding of the lining material to the pipe line.
As far as the method itself for satisfactorily applying a binder is concerned, several prior art methods come into question. U.S. Pat. No. 3,230,129 discloses a method for lining conduits wherein a conduit is previously filled with a binder and a resinous tube is inserted into the conduit from one end thereof while turning the tube inside out and pushing the binder forward thereby bonding the evaginated portion of the tube onto the inner surface of the conduit by the aid of the binder remaining on the inner surface thereof. However, this method has also a number of drawbacks. Firstly, the quantity and distribution of the binder cannot be controlled at all and a significant amount of the binder is wasted. Secondly, an extremely high pressure is required fo evaginating the tube while pushing the binder forward. Thirdly, when the pipe is inclined or curved vertically, the head pressure of the binder makes it difficult to evaginate the tube or fluctuates the fluid pressure for evagination so that the amount of the binder interposed between the conduit and the tube tends to vary.
U.K. Pat. No. 1,512,035 discloses a method for lining pipe lines wherein a binder is applied onto the inner surface of a pipe line from a rotary spraying unit moving along the inside of the pipe line and positioned just in front of the lining tube moving forward simultaneously with evagination. This method is advantageous in control of the amount of the binder used but has a drawback that this method wherein the spraying unit moves along the inside of the pipe line cannot be applied to pipe lines curved in several portions because the movement of the spraying unit becomes almost impossible or unstable in curved portions.
U.S. Pat. No. 4,135,958 discloses a method of lining passageways with a tube wherein a binder container moves along the inside of a passageway while supplying a binder to a reservoir formed in the uneverted portion of the tube also moving under eversion along the inside of the passageway in the same direction to the moving container. As the binder container used in this method is similar to the spraying unit used in the method of U.K. Pat. No. 1,512,035 just above mentioned, this method has the same drawback as in the method of the U.K. patent.
Japanese Patent Unexamined Publn. Nos. Sho. 55-91629 and 56-44621 disclose a method for lining pipe lines which is basically an improvement relating to the methods disclosed in U.S. Pat. No. 4,182,262; U.K. Pat. No. 1,044,645 and Japanese Patent Unexamined Publn. No. Sho. 55-90326. According to this improved method, a binder reservoir is formed in the interior space of a lining material in rear of the pressure container and a long pipe line with many curved portions can be lined. However, this method has the same drawbacks as those seen, for example, in U.K. Pat. No. 1,044,645 and Japanese Patent Unexamined Publn. No. Sho. 55-90326; a binder applied just before introduction of the pressure container onto the inner surface of a lining material is pushed backward by the internal fluid pressure when the lining material is introduced into the container. Further, this method is applicable only to the case of applying a binder onto the inner surface of the lining material just before its introduction into the pressure container and has to use an apparatus somewhat complex in structure when the length of the lining material is great.
Although the last mentioned type methods are fundamentally excellent in the lining treatment itself of a very long pipe line having curved portions, these methods are still unsatisfactory in respect of applying a sufficient amount of the binder evenly onto the inner surface of the lining material. Under these circumstances, there is a great demand for development of a new method which entirely overcomes the drawbacks of the prior art methods.